In early September 2006, a vice president of Wal-Mart sent a highly personal email to his boss through what he thought was a safe email account. "My Gmail is secure," Sean Womack assured Julie Ann Roehm, the company's senior vice president for marketing communications. "Write to me. Tell me something, anything.... I feel the need to be inside your head if I cannot be near you."

Roehm had persuaded the company to hire Womack only three months before. "I hate not being able to call you or write you," she replied. "I think about us together all of the time. Little moments like watching your face when you kiss me. I loved your voicemail last night and love the idea of memory and kept thinking/wishing that it would have been you and I there last night." Then she signed off, saying she had to take her two children to the park.

Unfortunately for Roehm and Womack, who were both married to other people, their intimate email exchanges would become public in a legal dispute between Roehm and their employer. Wal-Mart learned about the relationship while investigating Roehm for accepting gifts from an ad agency that received a huge contract with the retailer. Ultimately, Wal-Mart fired both execs for violating company policy and later accused them of carrying out a love affair on company time.

Largely overlooked in the furor was the role that Wal-Mart's internal security department had played in digging up the salacious details. This department, a global operation, was headed by a former senior security officer for the Central Intelligence Agency and staffed by former agents from the C.I.A., the Federal Bureau of Investigation, and other government agencies. (See our Spy Slang guide) A person familiar with the episode said in an interview that an ex-C.I.A. computer specialist was involved in piecing together the email evidence—which included copies of Womack's private Gmail messages, provided by his estranged wife—and that another former government agent had supervised the overall investigation.